package com.lixinyue.exer;

public class fuction {
    public static void main(String[] args) {
        int n=10;
        fuction fuction = new fuction();
        int ret=fuction.fucy(n);
        System.out.println(ret);
    }
    public int fucy(int n)
    {
        if(n==0)
        {
            return 1;
        }
        if(n==1)
        {
            return 4;
        }
        else{
            return (2*fucy(n-1)+fucy(n-2));
        }
    }
}
